OXIDIZED OIL-SHALE FOR REMOVAL OF NITROGEN-OXIDES IN COMBUSTION GAS STREAMS

Oxidized oil shale from the combustor in the Lawrence Livermore National Laboratory (LLNL) hot recycled solids (HRS) oil shale retorting process has been found to be a catalyst for removing nitrogen oxides from laboratory gas streams, using NH3 as a reductant. Oxidized Green River oil shale, heated at 10-degrees-C min-1 in an Ar/O2/NO/NH3 mixture (approximately 93%/6%/2000 ppm/4000 ppm) with a gas residence time of approximately 0.6 s, removed NO between 250 and 500-degrees-C, with maximum removal of 70% at approximately 400-degrees-C. Under isothermal conditions with the same gas mixture, the maximum NO removal was approximately 64%. When CO2 was added to the gas mixture at approximately 8%, the NO removal dropped to approximately 50%. However, increasing the gas residence time to approximately 1.2 s, increased NO removal to 63%. Nitrogen balances of these experiments suggest selective catalytic reduction of NO is occurring using NH3 as the reductant. These results are not based on completely optimized process conditions, but indicate that oxidized oil shale is an effective catalyst for NO removal from combustion gas streams using NH3 as the reductant. Parameters calculated for implementing oxidized oil shale for NO(x) remediation on the current HRS retort, indicate an abatement device is practical to construct.